Spark timer for hammers



y 5, 3948. v. w. BREITENSTEIN ETAL 2,442,284

SPARK TIMER FOR HAMMERS .Filed May 12, 1945 2 Sheets-Sheet 1 y 194& v. w. BREITENSTElN EI'AL 2,442,284

SPARK TIMER FOR HAMMERS Filed May 12, 1945 2 Sheets-Sheet 2 force.

Patented May 25, 1948 SPARK TIMER FGR HAMMERS VictorW. Breitenstein and Ralph F. Ingebretsen, Chicago, Ill., assignors to Francis N. Bard,-

Highland" Park, Ill.

Application-May 12, 19 15, ScrialNo. 593,386

12 Claims. 1

adapted to be engaged by a spring pressed roller connected to an ignition pointand which is forced outwardly by the cam to complete the timer circuit by engagement with a stationary ignition point. This spring was necessarily of heavy material to insure contact only when desired, and would, therefore, force the piston against the opposite wallof its chamber causing friction and wear on the contacting surfaces. The arrangement is especially objectionable when the hammer is cold and the oil init stiif or gluey as the force of the spring at such times was a factor in preventing the piston from returning rapidly. Furthermore the piston eventually became biased or cocked, resulting in wear on the piston rings.

The present invention eliminates such wear by providing a vertical groove in the piston, a side wall of which is formed with the cam surface, said wall being parallel with the axis of the piston. The roller n the timer actuating means engages this surface whereby the force is exerted against the piston tangentially and may be substantially equalized by another surface of the timer assembly engaging the opposite wall to ofisetsaid roller Furthermore, because of the novel construction of the invention the spring need not be asstrong as the one formerly employed, there beme less possibility of contact between the ignition points at any but the desired time.

Other objects, advantages and features of the invention. will be apparent from the following specification and drawings'in which:

Fig. l. is a fragmentary vertical elevation, partly in section of an internal combustion percussive tool embodying the invention.

Fig. 2 is a horizontal sectional view taken on the line 22 of Fig. 1.

Fig. 3 is a vertical sectional view taken on the line 3-3 of'Fig. 2 and Fig. 4 is a fragmentary view taken on the line 5-4 of Fig. 2.

The internal combustion hammer or percussive tool illustrated has a cylinder H1 provided with cooling 'fins file and having a piston hammer l I freely reciprocal'thereinand adapted to impart blows to a tool at the bottom of the hammer through the anvil I'Z. A piston return spring assembly l3 urges the. piston upwardly. The hammer is provided with the necessary manifoldpas- .sagestoenable. a combustion charg'eto be drawn 2 into the chamber I4 beneath the piston and thereafter transferred to the combustion chamber' i5 above thepiston through the passage N5, in accordance with knowntwo-cycle engine practies. The cylinder also has an exhaust port ll.

The hammer is provided with an ignition system including a spark plug [-8 and a timer 19. An ignition unit including a battery or other source of current and a buzzer operated spark coil'is connected in accordance with known practice-tothe hammer having a high tension and a low tension circuit therein. These circuits and the wiring therefor are so well known that it is not deemed necessary to show or describe them in connection with this invention which relates to: the means for causing. contact between the timer points. Likewise, we have only shown. that part of the hammer with which the invention is' directly associated. The hammer is of the same general type as those shown Mould Patents 1,868,754, and 1,997,072 and Charles Patents 2,180,034 and 2,,2,75,285 wherein the mode of operation of the hammer is fully described, and reference may be had to such patents and others to supplement this disclosure as to the general construction-and operation of suchhammers.

In the timer illustrated in the drawings, the cylinder H3 is provided with an opening 20 therethrough transverse to the axis of the cylinder; A hollow bearing member 2| having a flanged outer end 22 and a reduced semi-circular inner end 23 is inserted in this opening. A cover .or housing 2 s for the timer is placed on the flanged outer end 22 of the bearing member and the bearing member and cover are secured to the cylinder by nut and bolt connections 25.

The piston .is provided with a longitudinal groove 23 having a smooth side wall' 21; theopposite wall 23 having av recessed cam surface 28a. These walls are parallel and. at right angles to the rear wall, hence they are. not exactly radialiof the piston but are substantially radial and ,will be hereinafter so termed. Journaled in. the bearing member 2! is a shaft 28 having a flattened surface 38 at its outer end and with its inner .end

extending intothe groove in the piston. Extendwound around a reduced portion of the shaft 29 and tending to force the roller toward the cam surface of the groove (to the right as shown in Fig. 3) as well as urging the shaft toward the piston. An opening is provided near the other end of the shaft for the reception of a cotter pin to prevent the shaft extending too far into the groove 26 and contacting the rear wall thereof.

To one wall of the timer I9 is attached a spring arm 35 bearing a point 36. Extending through an opening in the opposite wall of the housing is a threaded member 31 on the inner end of which is a point 38 adapted to be contacted by the point 36, as hereinafter described. The member 31 is threaded through a sleeve member 39 havin an enlarged outer end and which is insulated from the sides of the opening in the housing by washers 40 and 4|. Nut 42 on the inner end of the sleeve, and nut 43 near the outer end of the member 36 maintain the sleeve in position in the opening. The member 31 is adjustable to vary the distance between the two points. Additional washers may be used on the sleeves as shown. The spring arm 35 bears against the outer end of the shaft 29 and when this arm contacts the circular portion of this'shaft the contact 36 is spaced from the contact 38. When, however, the piston is at the position where the cam surface 28a is opposite the roller 32, the roller is forced into said surface by the spring action and partially rotates the shaft 29 to present the flat surface 30 thereof to the spring arm 35 and the two points 36 and 38 contact each other and complete the low tension ignition circuit, the point 36 being grounded through spring arm 35 to the cylinder and the point 38 being connected by lug 44 on sleeve 39 to a wire (not shown) connected with said circuit.

It is apparent that the forces exerted by the timer assembly against the piston are in a tangential direction and will not tend to cause wear on the oppositeside of the piston and the cylinder wall adjacent thereto. Furthermore, the force of the spring is offset by the force applied by the end 23 of the bearing member which maintains the same pressure against the opposite wall of the piston. Furthermore, the spring 34 does not directly act to maintain the two points in spaced position as did the prior art spring. It merely acts to prevent the shaft 29 from turning, and as partial turning of the shaft will not result in any movement of the point 36, it is not necessary to have as strong a spring as that used formerly. This results in less wear on the roller and the parts it contacts.

While we have shown anddescribed certain embodiments of our invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

We claim:

1. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprisinga substantially radial surface on said piston providing a tangentially-acting cam surface; and means actuated by said cam surface to close said circuit.

2. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool,

means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprising a substantially radial surface on said piston providing a tangentially-acting cam surface; and means bearing against said surface and actuated thereby to close the circuit.

3. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprising a substantially radial surface on said piston providing a tangentially-acting cam surface; means -bearing against said surface and actuated thereby to close the circuit; and means bearing against another surface on said piston to equalize the force exerted by said first means.

4. The device claimed in claim 3 wherein the surfaces are opposite sides of a longitudinal groove in the piston.

5. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprising a surface on said piston substantially radial thereof and providing a tangentially-acting cam surface; a member in said cylinder and bearing against said cam surface in a direction tangential to the radius of the piston; and means actuated by said member to close said circuit.

6. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprising a longitudinal groove in said piston having a surface parallel with the axis of said piston and substantially radial thereof and providing a tangentially-acting cam surface; a shaft in said cylinder and extending into said groove; means cooperating with said cam surface to rotate said shaft; and means operable by the rotation of said shaft to close said circuit.

'7. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprising a longitudinal groove in said piston having a surface parallel with the axis of said piston and substantially radial thereof and providing a tangentially-acting cam surface; a shaft in said cylinder and extending into said groove; a roller on one end of said shaft and bearing against said cam surface whereby to rotate the shaft; and means actuated by rotation of the shaft to close the circuit.

8. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for ignit ing said charge, ignition apparatus therefor comprising a substantially radial cam surface on said piston; a longitudinal groove in said piston having a straight surface and an irregular surface both being generally parallel with the axis of the piston and substantially radial thereof, the lastmentioned surface providing a tangentially-acting cam surface; a member in said cylinder having a portion extending into said groove and contacting said straight surface; a shaft in said member and having a roller thereon contacting the cam surface whereby to rotate the shaft; and means actuated by the rotation of the shaft to close said circuit.

9. In an internal combustion percussive harnmer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprising a longitudinal groove in said piston having a surface parallel with the axis of said piston and substantially radial thereof and providing a tangentially-acting cam surface; a shaft in said cylinder and extending into said groove; means on the inner end of the shaft and cooperating with the cam surface to rotate said shaft; a fiat surface at the outer end of said shaft; and a member bearing against the outer end of the shaft and adapted to close said circuit when the shaft is rotated so that the flat surface thereon is presented to it.

10. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor comprising a longitudinal groove in said piston having a surface parallel with the aXis of said piston and substantially radial thereof and providing a tangentially-acting cam surface; a shaft in said cylinder and extending into said groove; means 6 on the shaft and cooperating with the cam surface to rotate the shaft; a pair of ignition points spaced from each other by said shaft; and means for causing one of said points to contact the other upon rotation of the shaft.

11. In an internal combustion percussive hammer having a cylinder, a piston reciprocable therein adapted to impart impacts to a tool, means for supplying said cylinder with a combustible charge and an ignition circuit for igniting said charge, ignition apparatus therefor, comprising: a surface on said piston substantially radial thereof and providing a tangentially-act ing cam surface; a cam follower in said cylinder and bearing against said cam surface and movable in a direction tangential to the radius of the piston; a switch adapted to open and close said circuit; and an actuating connection between said cam follower and said switch.

12. Apparatus of the character claimed in claim 11, wherein said actuating connection comprises a shaft mounted on said cylinder having its axis radial of said cylinder.

VICTOR W. BREITENSTEIN. RALPH F. INGEBRETSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,813,513 Saunders July '7, 1931 2,163,336 Charles June 20, 1939 2,175,741 Charles Oct. 10, 1939 2,216,641 Charles Oct. 1, 1940 

